Grantee Research Project Results
Final Report: Evaluation of Chitosan and Chitosan - Ag Electrospun Membranes for Lead And Bacterial Removal From Potable Water of Puerto Rico
EPA Grant Number: SU835325Title: Evaluation of Chitosan and Chitosan - Ag Electrospun Membranes for Lead And Bacterial Removal From Potable Water of Puerto Rico
Investigators: Valentin, Ricky , Vega Avila, Ana Lucia , Artes, Daniel , Suarez, Marielis
Institution: University of Puerto Rico - Mayaguez
EPA Project Officer: Hahn, Intaek
Phase: I
Project Period: August 15, 2012 through August 14, 2013
Project Amount: $14,916
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Research Category: Pollution Prevention/Sustainable Development , P3 Challenge Area - Chemical Safety , P3 Challenge Area - Safe and Sustainable Water Resources , P3 Awards , Sustainable and Healthy Communities
Objective:
According to a report of the Environmental Protection Agency (EPA) at least the 79% of the population of Puerto Rico had consumed, at some point, drinking water that does not meet the quality standards established by the local and federal regulations for water to human consume, which could potentially affect their health [6].
The quality of water sources in Puerto Rico is mainly affected by the presence of bacteria of fecal origin, nutrients and suspended sediments. However, a significant contribution to the presence of organic and inorganic compounds in the water comes from the use of fertilizers and pesticides in agriculture, mineral extraction, construction, and metal processing industries. The presence of Lead (Pb) in potable water mainly comes from pipes for water distribution found in old and new houses.
Treatment of polluted water it is not always enough to reach these quality standards, in the case of heavy metals such as lead and cooper, EPA reports violation to regulations for quality of drinking water in Puerto Rico, mainly associated with the use of inappropriate techniques for removal of these metals [7]. The younger are the main prejudiced by the consume of water contaminated with Pb and bacteria. High Pb levels can be the cause of damage to the brain and nervous system, slowed growth, headaches, etc. In adults it can be the cause of reproductive problems, nerve disorders, high blood pressure, problems with memory and concentration .
Diseases such as cholera, related with consume of water contaminated with bacteria of fecal origin are one of the main causes of death in infants in counties of the third world.
Because heavy lead it is not biodegradable, it is required to use physical or chemical treatments to remove it from contaminated water. Adsorption in filter membranes and in polymers is one of the most used methods; however the used and polluted adsorbents become a cause of soil contamination, because they are not biodegradable, which contribute to worsen the global environmental problem.
Chitosan and other biopolymers have been evaluated as adsorbents to remove toxic metals from contaminated water. Chitosan is a low cost biopolymer that presents bactericidal and metal adsorbent properties, biocompatibility and biodegradability. The last one characteristic gives to chitosan competitive advantage over synthetic polymers, which are a potential source of environmental pollution.
Taking advantage of the capacity of chitosan to binding aniones or cationes (depending on the pH), of its biocide effects and biodegradability, we will to designing the objective of this project is to determinate the effectiveness of electrospun chitosan nanofibers and electrospun Chitosan Ag membranes, to remove lead and bacteria from residential water in Puerto Rico.
Summary/Accomplishments (Outputs/Outcomes):
At this point of the project we have been able to successfully prepare continuous electrospun Chitosan-PEO and Chitosan-PEO-Ag membranes of approximately 5 cm x 10 cm x 15 μm (weight x length x thickness), water resistance of these electrospun membranes have been increased by mean of heat treatment, and FfiR tests have revealed that heat treatment apparently do not modify the chemical structure of chitosan membranes.
Diameter and morphology of the fibers was determined by mean of SEM. Average diameter of Chitosan-PEO fibers results to be 212 nm, while the average diameter of Chitosan-PEO-Ag fibers was 23 nm some differences in size and shape of the fibers and in the macroscopic appearance of the membranes were observed, these differences were attributed to the effect of relative humidity, and can potentially modify the pore size and surface area of the membranes and hence their final properties as a adsorbent and as a filter.
The bactericide effect of Ag nanoparticles in the membranes was probed by mean of antibiograma tests, electrospun Chitosan-PEO membranes containing 20% wt in Ag nanoparticles shown total inhibition to growth of E-colli, and other genres bacteria.
Currently we are focused in the characterization of the membranes, mainly lead adsorption tests (using ICP), surface area determination tests (Nitrogen adsorption test) and mechanical characterization. The results of the characterization are the base for the design of the water treatment/filtering system, because these will be allowing us to determine the lead capacity removal of the membranes, the quantity of membrane required for the treatment of a determined volume of water, the selection of the suitable design for the filter, either as a batch system or as a continuous system.
Conclusions:
P3 awards allows us the possibility of interact with researchers of interdisciplinary science, and provide to our team the possibility to apply the knowledge and contributing with an idea with the potential to positively impact the sustainability of communities in Puerto Rico.
Despite the facts that we have found several issues during the research such as our low capacity to produce large quantity of membranes, these issues have allowed us to create the basis for the phase II proposal.
Despite the fact the research it is still going on, we can to remark two main results:
- Nanocomposite electrospun membranes of Chitosan-Ag, containing 20% wt of Ag nanoparticles, have a complete biocide effect in E-colli, pseudomona, etc.
- Preliminary results in tests of lead adsorption from water containing pb at 15 ppb, 75 ppb and 150 ppb shown promising results for the pb binding capacity of Chitosan-PEO electrospun membranes.
Relevant Websites:
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The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.